Sample Alignment via Astigmatic Beam Detection
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Solution Overview
Problem
Existing sample alignment systems fail to simultaneously adjust Z-height and tip/tilt using astigmatism to sense Z-height and beam position, often requiring focused beams and oblique angles of incidence, which limits their precision and efficiency in determining sample characterizing parameters.
Innovation Solution
A system comprising a source of electromagnetic radiation, a stage for sample rotation and translation, a multi-element or single element position sensitive detector, and imaging means that introduces astigmatism to sense Z-height and tip/tilt by monitoring the geometric attributes of the reflected beam image, allowing for real-time adjustments to achieve precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a focused beam at oblique angle of incidence is used for sample alignment, then measurement precision of sample characterizing parameters is improved, but device complexity increases and ease of operation deteriorates
Solution Approach 1:
The patent replaces complex mechanical alignment systems with optical field-based detection. By using astigmatism in the electromagnetic beam and detecting beam position shifts on a detector, the system achieves precise alignment measurement without complex mechanical adjustment mechanisms, thereby improving measurement precision while reducing device complexity
Solution Approach 2:
The patent introduces an intermediary detection mechanism using astigmatic beam transformation. The beam position detector serves as an intermediary that translates subtle alignment changes into measurable position shifts, enabling high-precision measurement of sample characterizing parameters without direct complex mechanical intervention
2Manufacturing precision
If separate adjustment mechanisms are used for Z-height and tip/tilt alignment, then manufacturing precision is maintained, but ease of operation deteriorates and loss of time increases
Solution Approach 1:
The patent merges Z-height and tip/tilt alignment functions into a single integrated detection system. By using astigmatic beam detection that simultaneously responds to both axial and angular position changes, the system allows operators to adjust both parameters through a unified feedback mechanism, greatly improving ease of operation while maintaining manufacturing precision
Solution Approach 2:
The beam position detector serves multiple functions simultaneously: it detects both Z-height position and tip/tilt angular orientation through the astigmatic beam pattern. This multi-functionality eliminates the need for separate detection systems for each parameter, streamlining the alignment operation while preserving precision
3Measurement precision
If astigmatism is introduced into the electromagnetic beam for sensing, then measurement precision of Z-height and tip/tilt is improved, but device complexity increases
Solution Approach 1:
The patent changes the optical parameter of the electromagnetic beam by introducing astigmatism. This parameter change transforms the beam into an astigmatic beam that exhibits position-dependent pattern changes on the detector, enabling high-precision sensing of both Z-height and tip/tilt through simple detector position measurements without adding complex manipulation mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise alignment of samples by simultaneously adjusting Z-height and tip/tilt, improving the accuracy of sample characterizing parameters like PSI and DELTA, while allowing for visual monitoring of adjustments, thus enhancing the precision and efficiency of reflectometry and ellipsometry processes.
Implementation Method 1
monitoring the location of, and geometric attributes of an image pattern of a beam of electromagnetic radiation resulting from reflection of a beam directed onto said sample
Implementation Method 2
a means for introducing astigmatism into said beam of electromagnetism positioned between said source and multi-element detector or single element position sensitive detector
Data Source
AI summary
A system and method of use thereof that enables determining and setting sample alignment based on the location of, and geometric attributes of a monitored image formed by reflection of an electromagnetic beam from a sample and into an image monitor, which beam is directed to be incident onto the sample along a locus which is substantially normal to the surface of the sample.